Partial OFDM Symbol Recovery to Improve Interfering Wireless Networks Operation in Collision Environments

Abstract

The uplink data rate region for interfering transmissions in wireless networks has been characterised and proven, yet its underlying model assumes a complete temporal overlap. Practical unplanned networks, however, adopt packetized transmissions and eschew tight inter-network coordination, resulting in packet collisions that often partially overlap, but rarely ever completely overlap. In this work, we report a new design called Partial Symbol Recovery (PSR), that specifically targets the parts of data symbols that experience no interference during a packet collision. PSR bootstraps a successive interference cancellation (SIC) like decoder from these strong signals, thus improving performance over techniques oblivious to such partial packet overlaps. We have implemented PSR on the WARP software-defined radio platform and in trace-based simulation. Our performance evaluation presents experimental results from this implementation operating in a 12-node software network testbed, spread over two rooms in a non-line-of-sight indoor office environment. Experimental results confirm that our proposal PSR decoder is capable of decoding up to 60% of collided frames depending on the type of data and modulation used. This consistently leads to throughput enhancement over conventional Wi-Fi under different scenarios and for the various data types tested, namely downlink bulk TCP, downlink video-on-demand, and uplink UDP.